JP5839310B1 - Heat shrinkable tube with tearability - Google Patents

Abstract

The present invention provides a heat shrinkable tube made of a fluororesin having excellent tear straightness and high heat shrinkage at low temperatures. A tube including at least a fluororesin as a base resin, the thickness of a polymer entanglement unit observed in a cross section in the tube longitudinal direction after being contracted by 35% or more at 200 ° C. Is 1 to 9 μm. There are two main methods for controlling the entanglement strength of molecules. One is the control of the entanglement strength by controlling the dispersion of the additive for improving the tearing property, and the other is the control of the entanglement strength by controlling the entanglement between the molecules of the base resin. [Selection] Figure 3

Description

  The present invention relates to a heat-shrinkable tube made of a fluororesin and having a tearability, and more particularly, to a tearable tube having a heat-shrinkability made of a thermoplastic fluororesin.

  The tube which has tearability is utilized as a protection member until the time of use of various articles | goods. Among them, the tear tube made of fluororesin cannot be obtained with a tear tube made of hydrocarbon synthetic resin, and has such characteristics as heat resistance, chemical resistance, water and oil repellency, non-adhesiveness, and self-lubricating properties. have. Therefore, using these characteristics, it is used as an assembly tool for tubes such as precision instruments, protective tubes for electronic components, or catheters for introducing medical devices for introducing catheters, guide wires, etc., catheters, When no longer needed, the tube is torn and removed. In particular, the tear tube having heat shrinkability can reliably protect the internal article, but the heat shrink rate is sufficient to ensure sufficient adhesion between the heat shrink tube and the internal article. It needs to be big. Further, it is required that tearing can be easily performed without using a special instrument. The conventional tearing tube has a long cut along the entire length of the tube surface, and it has never been easy to tear.

In view of this, WO2013 / 077452 proposes a tube that can be torn without requiring an excessive break and has a high heat shrinkage rate.
However, if the required tube diameter is reduced depending on the application, there arises a problem that the straightness of tearing when the tube is torn is not sufficient. When the tube diameter is small, it is difficult to apply the force to open and tear the tube left and right (tearing) evenly to the left and right. Even in the case where the tearing force is applied unevenly, in order to reliably tear the entire length of the tube, excellent straightness of tearing is required. Also, when used as an assembly tool for catheters, etc., it must have high heat shrinkability in addition to straight tearability, and at the same time, it affects the dimensional accuracy of the finished assembled catheter. Dimensional accuracy is required. An error of several percent for both the inner diameter and length when contracted is a serious problem.

WO2013 / 077452 Publication

  In view of the above problems, the object of the present invention is to achieve 35% or more at 200 ° C. (40% or more as a more preferable form, 44% or more as a more preferable form, and 45% or more as a particularly preferable form). It is an object of the present invention to provide a tube that has the following heat shrinkability and is excellent in the straightness of tearing when the tube after being contracted is torn.

  As a result of studies to achieve the above object, the inventors have found that when the thickness of the entanglement unit of the polymer constituting the tube is in a specific range, the present invention has been completed. That is, the present invention is a tube containing at least a fluororesin as a base resin, and the entanglement thickness of the polymer observed in a cross section in the longitudinal direction after being contracted by 35% or more at 200 ° C. It is related with the heat-shrinkable tube which has tearability characterized by being 1 micrometer-9 micrometers.

  Since the tube of the present invention is excellent in straight tearing property, it is difficult to apply a tearing force evenly when removing the tube, and even a small diameter tube can be easily torn and removed.

It is a flowchart which shows an example of the manufacturing process of the tube of this invention. It is a figure which shows the observation method of the cross section of the tube of this invention. It is a photograph of the longitudinal section of the tube of the present invention shrunk by 35% or more at 200 ° C. It is a section schematic diagram of an expansion jig used for tube expansion. (A) shows an expansion jig of a type in which both ends of the tube are fixed, and (b) shows a type in which only one end is fixed. (A) is a diagram schematically showing the state of molecules in the tube when the tube of the present invention is contracted by 35% or more at 200 ° C. by dispersion control of ETFE dispersed particles, and (b) is (a). It is a figure showing the path of propagation when a torn. It is the schematic which shows an example of the shape of the front-end | tip dalmage of a dalmage screw. When the tube of the present invention is contracted by 35% or more at 200 ° C. by controlling the entanglement between FEP molecules, (a) is a diagram schematically showing the state of the molecules in the tube, and (b) is (a). It is a figure showing the path of propagation when a torn. It is the figure which represented typically the xy cross section of the tube of this invention shown in FIG. (A) is the tube which controlled the entanglement intensity | strength of the molecule | numerator by dispersion | distribution control of an ETFE dispersion particle, (b) is a schematic diagram of a part of the tube which controlled the entanglement intensity | strength of the molecule | numerator by control of the entanglement of FEP molecules. . It is a figure explaining the gap of a twin screw extruder screw.

  The polymer material exists in a state in which the molecular chains of the molecules constituting the polymer material are entangled in the shape of a yarn. Even in a molded body obtained by molding a polymer material, the state of molecular entanglement is maintained, and the physical properties of the molded body are greatly influenced by the structure of molecular entanglement. The present invention is an invention obtained by improving Patent Document 1 filed in-house, and provides a heat-shrinkable tube having excellent tearing straightness by controlling the strength of entanglement of molecules constituting the tube. The heat shrinkable tube excellent in tearing straightness of the present invention has a polymer entanglement unit thickness of 1 μm to 9 μm observed in a cross section in the tube longitudinal direction after being shrunk by 35% or more at 200 ° C. It is characterized by the fact that it shrinks by 40% or more, more preferably 44% or more, and particularly preferably 45% or more. As the tube becomes thinner, the shrinkage rate is less likely to occur. Therefore, it is preferable to achieve the shrinkage rate when the outer diameter of the tube is 1.40 mm or less.

  The tearable heat-shrinkable tube of the present invention is produced by the process shown in FIG. 1 as an example. In order to produce a heat-shrinkable tube having the characteristics of the present invention, it is necessary to control the entanglement strength of molecules as will be described later. There are two main methods for controlling the entanglement strength of molecules. One is the control of the entanglement strength by controlling the dispersion of the additive for improving the tearing property, and the other is the control of the entanglement strength by controlling the entanglement between the molecules of the base resin.

Hereinafter, the influence on the tearability of the tube by the molecular entanglement structure will be described with reference to the drawings.

  In FIG. 2, a method for observing the cross section of the heat-shrinkable tube will be described. Here, since the tube of the present invention is a tearable tube, its cross section can be observed by tearing. When the tube 1 is torn, a pulling force is applied to the notch 11 inserted in the center of the tube so as to widen the notch, and the tube 1 is torn in the z-axis direction (the longitudinal direction of the tube is the z-axis direction in FIG. 2). As an example, a photograph of a cross section including the z-axis when torn in the z-axis direction is shown in FIG.

  A method for controlling the entanglement strength by controlling the dispersion of the additive for improving the tearability will be described below.

  In the heat-shrinkable tube having tearability according to the present invention, at least a fluororesin is used as a base resin. Hereinafter, the present invention will be described with reference to an example in which a copolymer containing tetrafluoroethylene and hexafluoropropylene as constituent monomers (hereinafter referred to as “FEP”) is used as the base resin. When the tearability is insufficient, a polymer or filler incompatible with the base resin can be added to the base resin as an additive for improving the tearability.

  Examples of the polymer incompatible with the base resin include tetrafluoroethylene-ethylene copolymer (hereinafter referred to as “ETFE”), liquid crystal polymer, polyimide, polyetheretherketone, and polyamide. Examples of the filler include various inorganic fillers, glass fibers, and carbon fibers. The addition amount of the additive for improving the tearability added to FEP is preferably 20 wt% or less of the total amount including FEP. When the addition amount exceeds 20 wt%, the expansion rate of the tube cannot be increased, and a high heat shrinkage rate of 40% or more cannot be obtained.

  As an embodiment of the present invention, a tube using ETFE as an additive for improving tearability in the FEP of the base resin will be described below as an example.

  The tube is formed by the process shown in FIG. A twin screw extruder used to disperse ETFE in FEP adjusts the screw pattern and gap in order to finely disperse ETFE (hereinafter referred to as “fine dispersion”). As shown in FIG. 9, the gap 8 refers to the interval between the crests of the screw 7. It is preferable to provide a retention part in the screw pattern. This is formed into a tube with a single screw extruder. The formed tube is expanded using the expansion jig 2 shown in FIG. The tube 1 is passed through a pipe for regulating the outer diameter (hereinafter referred to as “outer diameter regulating tube 21”), and both ends of the tube 1 are set in sealing jigs 22 at both ends of the outer diameter regulating tube 21. And seal. While heating the expansion jig 2 in which the tube is set, compressed gas is injected from the injection port 23, and the inside of the tube 1 is pressurized and expanded in the radial direction.

  FIG. 5A schematically shows the state of molecules in the tube when the tube prepared as described above is contracted. The ETFE dispersed particles 3 exist in a state where they are stretched in the longitudinal direction of the tube (in FIG. 5, the longitudinal direction of the tube is the z-axis direction) after extrusion, and then the inner diameter of the tube is expanded to obtain FEP4 and A void is generated at a part of the interface of the ETFE dispersed particles 3. The void portion generated by the expansion is in a state where the FEP4 and the ETFE dispersed particles 3 are dissociated, and the molecular entanglement is cut off. By finely dispersing ETFE, a large number of voids exist in the tube. Further, as the state of entanglement of the FEP molecules, there are a portion 4a in which the FEP molecules are entangled and a portion 4b in which the molecules are not entangled after the extrusion molding, and the expansion makes the state of easy entanglement of the FEP molecules. Specifically, FEP, which is a fluororesin, has low cohesion between molecular chains, so that the molecular chains are slippery, and in the part where the entanglement of the FEP molecules is small, the molecular chains slide due to expansion, and the entanglement of the FEP molecules is released. Easy state.

  After the expanded tube is contracted, the state in which the molecular entanglement of the void portion generated at the interface between the FEP 4 and the ETFE dispersed particle 3 is cut off is maintained. In the void portion, the molecular entanglement disappears, and therefore the force for releasing the molecular entanglement (hereinafter referred to as “molecular entanglement strength”) is zero. Further, in the portion where the entanglement of the FEP molecules is easily undone, the entanglement strength of the molecules is close to zero. In the tube after contraction, a bundle of FEP molecules surrounded by a portion where the entanglement strength is 0 and a portion where the entanglement strength is weak is formed. When a notch is made at the end of the tube and a tearing force is applied using the notch as a starting point for tearing, the tear propagates along the bundle of FEP molecules. FIG. 5B shows the propagation path 5 when FIG. 5A tears.

  In the tube in which the molecular entanglement strength is controlled by controlling the dispersion of the ETFE dispersed particles 3, a bundle of molecules can actually be observed in a cross section including the z axis (FIG. 3 (tube cross section after contraction)). .

  A method for controlling the entanglement strength of molecules by controlling the entanglement between FEP molecules will be described below. There are mainly two methods for controlling the entanglement between FEP molecules.

  The first is a method of untangling FEP molecules in an extrusion mold while suppressing aggregation of ETFE. Specifically, FEP in which ETFE is finely dispersed is used, and a dalmage screw is used as an example of a method for suppressing aggregation of ETFE. The shape of the dull image is selected in consideration of the ability to reduce the shearing force as much as possible while suppressing aggregation. An example of the shape of the tip of the dalmage screw is shown in FIG. 6 (Dalmage 6). A die having a structure that suppresses the shear rate is used between the screw and the die. By suppressing the shear rate, the shear force is suppressed and the entanglement of the molecules entangled at the screw part is unwound.

The second method is to reduce molecular entanglement at the exit of the extrusion die. Specifically, molding is performed with a large Draw-Down-Ratio (DDR) during extrusion molding. DDR is obtained by the following equation.
Increasing DDR can reduce molecular entanglement in the tube radial direction. Here, at the time of fluororesin tube extrusion molding, it is usually written that the DDR is 3 to 15 (Nikkan Kogyo Shimbun Fluoropolymer Handbook P250). However, in the heat shrinkable tube having tearability according to the present invention, the DDR is preferably 50 or more. The tube formed in this way has many portions where the entanglement of FEP molecules is small in the radial direction.

  However, it is known that when a tube formed by extruding with a large DDR is processed into a heat shrinkable tube, the tube contracts greatly in the longitudinal direction during the heat shrinking operation of the tube. It is known that even when DDR is 30, shrinkage of 5% or more occurs (Japanese Patent Laid-Open No. 11-323053), and until now, molding with DDR of 50 or more has not been performed. Even in the tube of the present invention, when it is used as an assembly jig for a catheter, a large contraction in the longitudinal direction becomes a problem. Therefore, the expansion jig 2 shown in FIG. 4B is expanded so that a heat-shrinkable tube that does not contract in the longitudinal direction can be obtained even if the tube is extruded by increasing the DDR. A movable sealing jig 24 is attached to one end of the tube 1 and placed in the outer diameter regulating tube 21. Next, the other end of the tube 1 is attached to a sealing jig 22 set on the outer diameter regulating tube 21 to seal the inside of the tube. While heating the expansion jig 2 in which the tube is set, compressed gas is injected from the injection port 23, and the inside of the tube 1 is pressurized and expanded in the radial direction. The outer diameter of the movable sealing jig 24 is smaller than the inner diameter of the outer diameter regulating tube 21 and can be slid and moved in the regulating tube, and can be expanded while removing strain during molding in the tube longitudinal direction.

  FIG. 7A schematically shows the state of the molecules in the tube when the tube prepared by adjusting the state of molecular entanglement as described above is contracted. Compared to FIG. 5 (a), the number of ETFE dispersed particles 3 is small, and there are many portions 4b that are not entangled with FEP molecules. Compared with the case of controlling the molecular entanglement strength by controlling the dispersion of the ETFE dispersed particles 3, there are few portions where the molecular entanglement strength is 0 and there are many portions where the molecular entanglement strength is weak. In the tube after contraction, a bundle of FEP molecules surrounded by a portion where the molecular entanglement strength is weak and a portion where the molecular entanglement strength is 0 is formed. FIG. 7B shows the path 5 of the tear propagation when FIG. 7A tears. Tube tearing propagates along bundles of FEP molecules.

  Similar to the tube that controls the entanglement strength of molecules by controlling the dispersion of ETFE dispersed particles, a bundle of molecules is observed on the cross-section including the z axis in the tube that controls the entanglement strength of molecules by controlling the entanglement of FEP molecules. Is done.

  When the amount of ETFE added to the FEP is small, the ETFE dispersed particles 3 exist only sparsely, and most of them form a bundle of FEP molecules only by controlling the entanglement between the FEP molecules. In this way, even when the additive is reduced or without the additive, the entangled strength of the molecule by controlling the entanglement of the FEP molecules is surrounded by a portion where the entangled strength of the molecule is weak in the tube after contraction. It is possible to obtain heat-shrinkable tubes with bundles of FEP molecules that have been made.

  FIG. 8 schematically shows a part of the xy cross section of the tube of FIG. FIG. 8A is a schematic diagram of a tube in which the molecular entanglement strength is controlled by controlling the dispersion of the ETFE dispersed particles 3, and the ETFE dispersed particles 3 are scattered in the FEP4 of the base resin. FIG. 8B is a schematic diagram of a tube in which the entanglement strength of the molecules is controlled by controlling the entanglement between the FEP molecules, and there is no entanglement of the FEP molecules in the base resin 4 in which the entanglement of the FEP molecules is reduced. Point 4b exists. The point 4b in which the ETFE dispersed particles 3 in FIG. 8 (a) and the FEP molecules in FIG. 8 (b) are not entangled is a point where the entanglement strength of the molecules is 0 or close to 0, and the entanglement strength of the molecules is between them. There is a large base resin 4. The thickness of the bundle of FEP molecules surrounded by the portion where the molecular entanglement strength is weak and the portion where the molecular entanglement strength is 0 (hereinafter referred to as “thickness of polymer entanglement unit”) is ETFE dispersed particle 3 or FEP. Depends on the spacing between points 4b where there is no entanglement of molecules. The thickness of the polymer entanglement unit correlates with the straightness of tearing of the tube. In order to impart excellent tear straightness to the tube after being contracted by 35% or more at 200 ° C., the thickness of the polymer entanglement unit needs to be 1 μm to 9 μm. It is preferably 1 μm to 7 μm, more preferably 1 μm to 6 μm, and particularly preferably 1 μm to 4 μm.

  When the thickness of the unit of the polymer entanglement is too large, it means that the strength of the molecular entanglement is 0 or a point interval close to 0 is large, and the direction of propagation of tearing fluctuates and the straightness of tearing is poor. . Moreover, when the thickness of the molecular entanglement unit is too small, it is not preferable because the strength of the entire tube is also small, and it becomes difficult to process and handle the tube such as expansion.

(Measurement of polymer entanglement unit thickness)
The thickness of the polymer entanglement unit was calculated by measuring the cross-sectional shape in the tube longitudinal direction and displaying the cross-sectional shape as a waveform. This will be described below with reference to FIG. For the shape of the cross section, scan in the y-axis direction of FIG. 3 using a confocal microscope (H1200 manufactured by Lasertec Corporation, objective lens 100 times), and the height direction of the cross section (in the Z direction in the surface shape measurement) Called). The center value of the width in the Z direction of the waveform in the measurement range was calculated and the center line was drawn. The center value was calculated by excluding the peak having the maximum value of the waveform obtained in the measurement range and the peak having the minimum value. The distance from the point where the center line and the waveform intersect to the point where the next center line intersects, that is, the length of the center line that is the width of one peak or valley, is the thickness of the polymer entanglement unit. .
(Tearing straightness test)
In order to judge more clearly whether or not sufficient tearing straightness can be obtained when tearing a small-diameter tube, the following method was used. A cut having a length of 40 mm is provided at one end of a sample having a length of 1000 mm. The notch is provided in the center of the tube in parallel with the longitudinal direction of the tube using a jig. From the notch, tear to the other end of the tube at a speed of 200 mm / min. Each of the two pieces of torn tube is weighed to determine the weight ratio. It can be judged that the closer the ratio is to 50% vs. 50%, the higher the straightness of tearing. To tear small diameter tubes, the ratio should be in the range of 50% to 50% to 45% to 55%. When the ratio is in the range of 50% to 50% to 48% to 52%, and further in the range of 50% to 50% to 49% to 51%, straight tearing performance is improved.

Example 1
(Production of molding material)
Tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEI-130J manufactured by Mitsui DuPont Fluorochemical) and tetrafluoroethylene-ethylene copolymer (ETFE: C-55AP manufactured by Asahi Glass Co.), FEP / ETFE weight ratio = 80/20 and mixed well with a tumbler. This was put into a twin screw extruder having a cylinder diameter of 20 mm, extruded at a screw rotation speed of 45 rpm and a die temperature of 320 ° C., and pelletized. A screw having a pattern in which four retaining portions were provided was used, and a gap was set to 0.5 mm.
(Sample tube forming)
Using the prepared pellet, tube forming was performed by a single screw extruder having a cylinder diameter of 20 mm. As the screw, a full flight screw was used, and tube formation was performed by a sizing plate method at a screw rotation speed of 10 rpm, a die temperature of 390 ° C., and a draw-down ratio DDR10. A tube having an inner diameter of 0.5 mm, an outer diameter of 0.9 mm, and a wall thickness of 0.2 mm was obtained.
(Expansion of sample tube)
The formed tube is attached to the same type of expansion jig as shown in Fig. 4 (a), and the inside diameter of the tube is expanded by injecting pressurized nitrogen into the inside while heating from the outside of the jig, and cut to a length of 1000 mm. did. The outer diameter of the tube was 1.33 mm.
(Sample tube shrinkage)
Ten samples were randomly extracted from the expanded sample tube, and after measuring the inner diameter, the sample tube was heated and contracted for 20 minutes in a thermostatic bath at 200 ° C. to obtain a sample tube. The shrinkage rate was calculated by measuring the inner diameter after shrinkage.

Example 2
(Production of molding material)
It was produced in the same manner as in Example 1 except that the FEP / ETFE weight ratio was mixed at the FEP / ETFE weight ratio = 90/10.
(Sample tube forming)
A dalmage screw was used as the screw of the single screw extruder, and the draw ratio DDR was set to 10. The other conditions were the same as in Example 1.
(Sample tube expansion / contraction)
It carried out on the conditions similar to Example 1. The outer diameter of the expanded tube was 1.39 mm.

Example 3
(Production of molding material)
It was produced in the same manner as in Example 1 except that the FEP / ETFE weight ratio was mixed at FEP / ETFE weight ratio = 97/3.
(Sample tube forming)
A dull image screw was used as the screw of the single screw extruder, and the draw ratio DDR was set to 50. The other conditions were the same as in Example 1.
(Expansion of sample tube)
Mount the molded tube on the same type of expansion jig as in Fig. 4 (b), inject pressurized nitrogen into the inside while heating from the outside of the jig, expand the inner diameter of the tube, and cut to a length of 1000 mm did. The outer diameter of the tube was 1.36 mm.
(Sample tube shrinkage)
It carried out on the conditions similar to Example 1.

Comparative Examples 1-3
(Production of molding material)
Tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEI-130J manufactured by Mitsui Dupont Fluorochemical) and tetrafluoroethylene-ethylene copolymer (ETFE: C-55AP manufactured by Asahi Glass) are mixed in each weight ratio. Then, this was put into a twin screw extruder having a cylinder diameter of 20 mm and extruded at a screw rotation speed of 45 rpm and a die temperature of 320 ° C. to form a pellet. The screw used was a pattern with a gap of -1.5 mm (overlapping portion of the screw was 1.5 mm) and no retention portion.
(Sample tube forming)
Using the prepared pellets, tube forming was performed by a single screw extruder having a cylinder diameter of 20 mm. As the screw, a full flight screw was used, and tube formation was performed by a sizing plate method at a screw rotation speed of 10 rpm, a draw-down ratio DDR10, and a die temperature of 390 ° C. A tube having an inner diameter of 0.5 mm, an outer diameter of 0.9 mm, and a wall thickness of 0.2 mm was obtained.
(Expansion of sample tube)
The molded tube is attached to the same type of expansion jig as shown in Fig. 4 (a), and the inside diameter of the tube is expanded by injecting pressurized nitrogen into the inside while heating from the outside of the jig, and cut to a length of 1000 mm. did.
(Sample tube shrinkage)
Ten samples were randomly extracted from the expanded sample tube, and after measuring the inner diameter, the sample tube was heated and contracted for 20 minutes in a thermostatic bath at 200 ° C. to obtain a sample tube. The shrinkage rate was calculated by measuring the inner diameter after shrinkage.

For each of the prepared sample tubes, the thickness of the molecular entanglement unit was determined based on the method for measuring the thickness of the molecular entanglement unit described above. Further, the tear straightness was measured based on the above-described test method for tear straightness. The results are shown in Table 1.
In the tubes of Examples 1 to 3 of the present invention, a heat shrinkage rate of 40% or more was obtained at 200 ° C., and the thickness of the polymer entanglement unit was 1 μm to 9 μm. The ratio of the weight of the torn tube, which shows the straightness of tearing of the tube, was 50% to 50% to 49% to 51%, and very good straightness of tearing was obtained. In contrast, the heat-shrinkable tubes of Comparative Examples 1 and 2 having a conventional tearable tube have a heat shrinkage ratio of 40% or more, but the thickness of the polymer entanglement unit is too large. The straightness was not sufficiently obtained, and the weight ratio of 45% to 55%, which is a standard for obtaining sufficient straightness of tearing even when a small-diameter tube was torn, was off. In Comparative Example 3, straight tearability was obtained, but it was not possible to expand 20% or more, and a heat shrinkage rate of 40% or more could not be obtained (the shrinkage rate was not improved even after heating at 200 ° C. for 1 hour). 21%).

Example 4
(Production of molding material)
Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter referred to as “PFA”) (Mitsui Fluoro DuPont PFA-340J) and C-55AP were mixed at a PFA / ETFE weight ratio of 97/3. It was produced in the same manner as in Example 3.
(Sample tube forming)
Molded in the same manner as in Example 3.
(Expansion of sample tube)
Expanded as in Example 3. The outer diameter of the tube was 1.18 mm.
(Sample tube shrinkage)
The same operation as in Example 3 was performed.
When each measurement was performed on the prepared sample tube, the thickness of the polymer entanglement unit was 8 μm, the straightness of tearing was 52:48, and the shrinkage rate was 35%. Regardless of the type of fluororesin, there was a correlation between the thickness of the polymer entanglement unit and the straightness of tearing.

  The fluororesin tear tube of the present invention has high heat shrinkability and good tear straightness, so that it can be easily mounted and removed after use, and is suitable as an assembly jig for catheters and the like. .

1: tube, 2: expansion jig, 21: outer diameter regulating tube, 22: sealing jig, 23: injection port, 24: movable sealing jig, 3: ETFE dispersed particles, 4: FEP, 5: tear propagation 6: Dalmage, 7: Screw, 8: Gap

Claims (5)

In a tube containing at least a fluororesin as a base resin, the shrinkage rate when heated at 200 ° C. is 35% or more, and in the cross section in the longitudinal direction of the tube after being shrunk by 35% or more at 200 ° C. A heat-shrinkable tube having a tearing property, characterized in that the thickness of the polymer entanglement unit is 1 μm to 9 μm. In a tube containing at least a fluororesin as a base resin, the shrinkage rate when heated at 200 ° C. is 44% or more, and in the cross section in the tube longitudinal direction after being shrunk by 44% or more at 200 ° C. A heat-shrinkable tube having a tearing property, characterized in that the thickness of the polymer entanglement unit is 1 μm to 9 μm. The heat-shrinkable tube having tearability according to claim 1 or 2 , wherein the fluororesin is a copolymer containing tetrafluoroethylene and hexafluoropropylene as constituent monomers. The tube having tearability according to any one of claims 1 to 3 , wherein a ratio representing straightness of tearing is in a range of 50% to 50% to 48% to 52% . Wherein the outer diameter of the tube is less than 1.39 mm, the heat shrinkable tube having a tear resistance according to claim 1-4.